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How to Calculate Cubic Feet

To find the volume of a room, or any orthogonal object, you need to find out how big it is in cubic feet.


  • Step 1: Calculate the volume of a sphere by multiplying four-thirds times pi times the cube of the sphere's radius. Now you can use these calculations in every day life.
  • FACT: The English measurement system defined a foot as 12 times the length of the forefinger from the tip to the first joint.
  • Step 2: Find the cubic footage of a cylindrical object by multiplying the height times pi times the square the radius.
  • Step 3: Use the cubic foot measurement in practical applications. For example, if you were planning to create a sidewalk, you could divide the total cubic feet by the coverage per bag of cement to determine how many bags you would need. That's a concrete example.
  • TIP: Convert all measurements to feet.
  • Step 4: Calculate the object's volume. In the case of an orthogonal shape, multiply the three dimensions -- length, width and height. For other shapes, use a geometric formula.
  • Step 5: Measure the object's dimensions. In the case of an orthogonal shape, measure the length, width and height of the room or space you're working with. Use geometric formulas and the associated dimensions for computing the volumes of non-orthogonal shapes.

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